Conformational analysis of methylboronic acid and its acyclic esters

With the use of RHF/6-31G(d) and MP2/6-31G(d)//RHF/6-31G(d) semi-empirical (AMI) and non-empirical quantum chemical approximations conformational isomerization of methylboronic acid and its methyl, isopropyl, tert-butyl, and phenyl esters is studied. With the exception of the tert-butyl analogue, the potential energy surface of molecules in these compounds, is shown to contain three minima that correspond to planar and near-planar conformers: cis-cis, trans-trans, and cis-trans, with the latter being the main one. The minima are separated by two conformational isomerization barriers corresponding to the orthogonal arrangement of one of the OH(OR) groups.     

Vibrational spectra of the trans-trans and trans-cis conformers of dimethyl fumarate

Infrared and Raman spectra of dimethyl fumarate (DMFU) have been recorded in the temperature range 12–390 K. The solid state spectra are consistent with the trans-trans conformation. However, in the liquid phase (melt or solution in CCl₄) and in the vapour phase, additional infrared and Raman bands were observed due to the presence of the trans-cis conformer. For the trans-trans conformer the observed spectra have been assigned on the basis of a C_2h molecular symmetry. A normal coordinate analysis of trans-trans DMFU has been carried out using a modified Urey- Bradley force field to assist in the assignment. Observed frequencies for the trans-cis conformer have been assigned on the basis of a structure of C_s symmetry.     

The effects of substituents upon the ultraviolet spectra of conjugated dienes : The applicability of woodward's rules

Data on the electronic spectra of conjugated dienes di-substituted with saturated hydrocarbon chains of increasing length have been collected from the literature. One aspect of these spectra, the fact that the absorption maximum for a cis-cis compound lies at longer wavelengths than that for the corresponding trans-trans, has received some attention in the literature, but no quantitative explanation of the observation has been offered. A second fact, that increasing substituent chainlength results in a steady shift of the absorption maxima to long-wavelength limits of ~235nm for cis-cis, ~233nm for cis-trans and trans-cis and ~ 231 for trans-trans, appears to have gone unremarked in spite of the fact that, as a result. Woodward's rules are not obeyed by such compounds.Quantitative interpretations of both these phenomena are described.     

Photochemical- and pH-switching Properties of a New Photoelastic Ligand Based Upon Azobenzene. Basicity and Anion Binding

Abstract

The synthesis of a new cylindrical macrotricyclic ligand (L) based upon two 1,4,7,13-tetramethyl-1,4,7,10,13,16-hexaazacyclooctadecane rings connected via two azobenzene pillars is described. The ligands displays photoelastic properties: light absorption at 366 nm produces trans→cis isomerization of the azobenzene moieties with formation of trans-cis (L _E-Z ) and cis-cis (L _Z-Z ) isomers. Recovery of the thermodynamically more stable trans-trans (L _E-E ) isomer can be obtained by thermal back-isomerization or visible light (430 nm) absorption. The isomeric composition of L solution depends upon pH: for pH < 5.5 the L _E-E form is the unique species in solution, while increasing amounts of Z species are formed at increasing pH. The protonation constants of L _E-E have been determined in 0.1 mol dm^?3 Me₄NNO₃ solution at 298.1 ± 0.1 K. The protonated species of L form stable inclusion complexes with anionic species such as [Co(CN)₆]^3?.     

New complexes of fullerences C60 and C70 with CoII and MnII tetraphenylporphyrinates and their ESR study

Complexes of fullerenes C₆₀ and C₇₀ with cobalt(II) and manganese(II) tetraphenylporphyrinates of compositions Mn(TPP)·(C₆₀)₂(CS₂)_1.5 (1), Mn(TPP)·C₇₀(CS₂) _x , wherex<=1.25 (2), Co(TPP)·C₆₀(CS₂)_0.5 (3), and Co(TPP)·C₇₀(CS₂) _x , wherex<0.25 (4), were synthesized and studied by ESR spectroscopy. At 77 K, complexes1 and2 have singlet ESR spectra characteristic of the low-spin (S=1/2) state of Mn^II, withg=2.002 and linewidths of 250 G and 300 G, respectively, and differing significantly from that of the initial Mn^II(TPP) (g ₁=5.9 andg=2.0,S=5/2). The spectra of complexes1 and2 exposed to oxygen exhibit hyperfine structure due to interaction with⁵⁵Mn and¹⁴N nuclei. The ESR spectra of complexes3 and4 are asymmetric (<g>=2.4, ΔH _pp=(500–600) G), which is due to the overlap of parallel and perpendicular spectral components. The absence of ESR signals from C₆₀ ^.− and C₇₀ ^.− radical anions makes it possible to conclude that the formation of complexes1–4 is not accompanied by electron transfer from Co(TPP) and Mn(TPP) to fullerences C₆₀ and C₇₀. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 722–725, April, 1999.     

An ab initio Molecular Orbital Study of the Conformational Properties of all-( Z )-Cyclododeca-1,4,7,10-tetraene

 Ab initio HF/6-31G^* and MP2/6-31G^*//HF/6-31G^* methods were used to calculate the structure optimization and conformational interconversion pathways for all-(Z )-cyclododeca-1,4,7,10-tetraene. This compound adopts the symmetrical crown (C _4v) conformation. Ring inversion takes place via symmetrical intermediates, such as boat-chair (BC, C _s) and twist (C _2h) conformers and requires about 22.3 kJ · mol⁻¹. The calculated strain energies for BC and twist conformers are 5.9 and 13.5 kJ · mol⁻¹. The results of semiempirical AM1 calculations for structural parameters and relative energies of the important geometries of the title compound are in good agreement with the results of ab initio methods.     

Ab initio HF-SCF study of naphthazarin: Geometries,isomerism, hydrogen bonding,and vibrational spectrum

The structural properties and intramolecular hydrogen bonding of a series of structures of naphthazarin molecule were investigated by ab initio HF-SCF methods. The geometries of theC _2v ,C _2h ,D _2h , andC _s symmetry structures were optimized using split-valence basis sets. MP2/6-31G^*// HF/6-31G single-point energy calculations indicate that theC _2v isomer (5,8-dihydroxy-1,4-naphthoquinone) is the lowest energy structure of the molecule and that theC _2h symmetry one (4,8-dihydroxy-1,5-naphthoquinone), lying 37 kJ/mol above theC _2v form, is the other stable isomer of naphthazarin. At the HF/6-31G level, the intramolecular proton exchange between two equivalentC _2v structures is a two-step process where each proton can be independently transferred through an unsymmetrical potential having a 1,5-quinone intermediate, theC _2h symmetry structure, and two equivalent transition states ofC _s symmetry, with a barrier height equal to 38 kJ/ mol (MP2/6-31G^*//HF/6-31G). The study of naphthazarin molecule is flanked by a theoretical investigation on theC _2v andC _2h isomers of the parent naphthoquinone and dihydroxynaphthalene molecules. The SCF vibrational spectrum of the ground state of naphthazarin, harmonic frequencies, and infrared and Raman band intensities were computed at the HF/6-31G level. The results of the calculations are compared with the matrix isolation FT-IR spectroscopy measurements and with the infrared and Raman spectra of the crystal molecule.     

An ab initio study of the structure,dissociation energy,and heat of formation of Na2S

The equilibrium geometries and fundamental frequencies of Na₂S are calculated at HF, MP2(FC, FU), and MP3 with the 6–31G(d) basis set and at HF and MP2(FC, FU) with the 6–31G(d) basis set, respectively. The total energy at MP2(FU)/6–31G(d)-optimized geometry is computed at MP4 with 6–311G(d, p), 6–311 + G(d, p), and 6–311G(2df, p), at QCISD(T)/6–311G(d, p), and at MP2/6–311G(3df, 2p) levels, respectively. The dissociation energy, the atomization energy, and the heat of formation for Na₂S are evaluated using the G1 and G2 models. The calculated results indicated that Na₂S in its ground state was a bent structure (C_2v). Electron correlation corrections on the bending angle are very significant. The equilibrium geometrical parameters are R_e(Na-S) = 2.45 Å and ∠Na-S-Na = 111.13° at the MP2(FU)/6–31G(d) level. The theoretically estimated dissociation energy, total atomization energy, and heat of formation are 67.07, 117.55, and 0.35 kcal mol⁻¹, respectively, at 298.15 K. © 1997 John Wiley & Sons, Inc.     

An ab initio Molecular Orbital Study of the Conformational Properties of all-(Z)-Cyclododeca-1,4,7,10-tetraene

Summary.  Ab initio HF/6-31G^* and MP2/6-31G^*//HF/6-31G^* methods were used to calculate the structure optimization and conformational interconversion pathways for all-(Z )-cyclododeca-1,4,7,10-tetraene. This compound adopts the symmetrical crown (C _4v) conformation. Ring inversion takes place via symmetrical intermediates, such as boat-chair (BC, C _s) and twist (C _2h) conformers and requires about 22.3 kJ · mol⁻¹. The calculated strain energies for BC and twist conformers are 5.9 and 13.5 kJ · mol⁻¹. The results of semiempirical AM1 calculations for structural parameters and relative energies of the important geometries of the title compound are in good agreement with the results of ab initio methods. Received July 9, 2001. Accepted September 26, 2001     

Synthesis,characterization, and structural determination of copper(II) complexes with alkyl derivatives of hydroxybenzophenones

Four mononuclear copper(II) complexes, [Cu(LFQM-115)₂] (1), [Cu(LFQM-116)₂] (2), [Cu(LFQM-117)₂] (3) and [Cu(octyloxy)₂] (4) [LFQM-115 = 2-hydroxy-4-O-methylbenzophenone (C₁₄H₁₁O₃), LFQM-116 = 2-hydroxy-4-O-butylbenzophenone (C₁₇H₁₈O₃), LFQM-117 = 2-hydroxy-4-O-(33-dimethylallyl)benzophenone (C₁₈H₁₈O₃) and octyloxy = 2-hydroxy-4-O-octylbenzophenone (C₂₁H₂₅O₃)], have been prepared and investigated by infrared spectroscopy, thermal analysis, and powder and single crystal X-ray diffraction. Even though the synthesis and infrared analysis of 1, 2, and 4 have been reported previously, their crystal structures were elucidated for the first time here. In addition, the crystal structures of LFQM-116 and LFQM-117 were also determined by single crystal X-ray diffraction. The pseudo-translational symmetry found in LFQM-116 and the isomorphism between LFQM-115 and LFQM-117 are discussed. The complexes were prepared from a reaction of copper(II) nitrate trihydrate and the respective ligand in a (1:2) molar ratio in methanol (for 1 and 2) or THF (for 3 and 4) with addition of NaOH. Furthermore, crystallographic studies show that each copper(II) exhibits a square planar geometry, coordinated by four oxygens of two ligands. The nature and crystal packing of the intermolecular interactions are discussed. Compounds 2 and 3 are isomorphic crystals and all structures have the same supramolecular synthon.     

双(取代水杨醛)间苯二甲酰腙有机锡配合物的一锅溶剂热法合成、结构和荧光性质

以间苯二甲酰肼、取代水杨醛和有机锡前体化合物进行一锅溶剂热法反应,合成了5个双（取代水杨醛）间苯二甲酰腙有机锡配合物m-Ph （CONH-N=CH （o-O） PhR¹）（SnR²）₂：R¹=Naphth,R²=Cy （1）; R¹=3-t-Bu,R²=n-Bu （2）; R¹=5-F,R²=Ph （3）; R¹=4-Cl,R²=Ph （4）; R¹=3-t-Bu,R²=Ph （5）。经元素分析、红外光谱、（¹H、¹³C和¹¹⁹Sn）核磁共振谱表征,并用X射线衍射方法确证了配合物1~5的晶体分子结构。配合物1~4为三斜晶系P1空间群,配合物5为单斜晶系P2₁空间群。中心锡与配位原子组成五配位畸形三角双锥构型。将水杨醛酰腙链与有机锡配位形成远离中心苯环的构型称为"反式",将与中心苯环取向相同的构型称为"顺式"。通过C1-C2或C4-C8单键旋转,中心苯环上的2个配位链发生构型翻转。配合物1形成"反-反"式构型,配合物2形成"顺-顺"式构型,配合物3、4和5形成"顺-反"式构型。荧光研究表明,配合物具有发光性能,特别是配合物1和4的有机溶液具有很强的荧光性能。     

Ab initio molecular orbital calculations of 3,4-dihydro-1,2-dioxin, 3,6-dihydro-1,2-dioxin, 4H-1,3-dioxin (1,3-diox-4-ene), and 2,3-dihydro-1,4-dioxin (1,4-dioxene)

Optimized geometries and total energies for 3,4-dihydro-1,2-dioxin ( 1 ), 3,6-dihydro-1,2-dioxin ( 2 ), 4H-1,3-dioxin (1,3-diox-4-ene, 3 ), and 2,3-dihydro-1,4-dioxin (1,4-dioxene, 4 ) were calculated using ab initio 3-21G, 6-31G*, and MP2/6-31G*//6-31G* methods. The half-chair conformers of 1 (C₁), 2 (C₂), 3 (C₁), and 4 (C₂) are more stable than their respective planar structures [ 1 (C_s), 2 (C_2v), 3 (C_s), and 4 (C_2v)]. Among the four isomers 1 – 4 , the half-chair conformer of 3 is the most stable. It is 53.1, 54.6, and 3.4 kcal mol⁻¹ more stable than 1 , 2 , and 4 , respectively. The largest energy difference (19.0 kcal mol⁻¹) is observed between the half-chair and planar conformers of 2 . The boat conformers of 2 and 4 are less stable than their respective half-chair conformers, but are more stable than their planar structures. Hyperconjugative orbital interactions (anomeric effects) contribute to the greater stability of 3 (n_O(3) →σ*_C(2)—O(1), n_O(3)→σ*,n _O(3)→σ*) and of 4 (n_O(1)→ σ*). The ab initio calculated structural features of the half-chair conformations of the dihydrodioxins 1 – 4 are compared with the half-chair conformations of cyclohexene and the chair conformations of cyclohexane, oxacyclohexane (tetrahydropyran), 1,2-dioxacyclohexane (1,2-dioxane), 1,3-dioxacyclohexane (1,3-dioxane), and 1,4-dioxacyclohexane (1,4-dioxane) © 1997 by John Wiley & Sons, Inc. J Comput Chem 18 : 1392–1406, 1997     

Gold(III)pentafluorophenylarylazoimidazole: Synthesis and spectral (H, C, COSY, HMQC NMR) characterisation

Reaction of [Au^III(C₆F₅)₃(tht)] with RaaiR′ in dichloromethane medium leads to [Au^III(C₆F₅)₃ (RaaiR′)] [RaaiR′=p-R-C₆H₄-N=N-C₃H₂-NN-l-R′, (1-3), R = H (a), Me (b), Cl (c) and R′= Me (1), CH₂CH₃ (2), CH₂Ph (3), tht is tetrahydrothiophen]. The nine new complexes are characterised by ES/MS as well as FAB, IR and multinuclear NMR (¹H,¹³C,¹⁹F) spectroscopic studies. In addition to dimensional NMR studies as¹H,¹H COSY and¹H¹³C HMQC permit complete assignment of the complexes in the solution phase.     

Infrared spectral identification of the high-energy conformer of <Emphasis Type="Italic">gauche,Trans,trans,Trans,gauche</Emphasis>-octa-1,3,5,7-tetraene

Scaled quantum mechanical force field (SQM-FF) vibrational analyses of the gauche,Trans,trans,Trans,gauche-conformers of octa-1,3,5,7-tetraene (I) with C _i and C ₂ symmetry at the HF/6-31G//HF/6-31G computational level were used to identify the rotational isomer observed in the IR spectrum of this excited molecule in the solid state. Geometry optimizations at the MP2(FC)/aug-cc-pVDZ level show that the two non-planar structures of gTtTg-I have the terminal -CH=CH₂ moieties rotated by ∼30.6° with respect to the remainder of the nearly planar skeleton. The MP2 and HF energies of the C ₂ conformer are slightly lower than the corresponding values of the C _i conformer. A set of the experimental wavenumbers relating to the C ₂ conformer was determined by the detailed analyses of the experimental IR spectra of compounds obtained by Datta et al. via photolysis of 1,3,5-cycloterraene and bicycle[4.2,0]octa-2.4-diene. The available experimental wavenumbers correlate better with the results of our SQM-FF calculations at the HF/6-31G level for the conformer with C ₂ symmetry than for the conformer with C _i symmetry. In further support of these results, the van der Waals molecular volume of the C ₂ conformer was calculated to be somewhat smaller than the volume of the C _i conformer, suggesting that in the solid state, where the close-packing principle comes into play, the C ₂ conformer would be preferred.     

Oxidative cross-coupling of some 2,6- and N,N-disubstituted aniline derivatives with 4-aminophenol mediated by cerium(IV) ions in aqueous perchloric acid

Summary The mechanism of the oxidation of mixtures of 2,6-dimethylaniline (1), N,N-dimethylaniline (2), 2,6-diethylaniline (3), N,N-diethylaniline (4), N-methylaniline (5), 2,6-difluoroaniline (6), and 2,3,5,6-tetrafluoroaniline (7) with 4-aminophenol (8) by cerium(IV) ions in aqueous perchloric acid has been investigated. The indoaniline salts [O=C₆H₄=N-C₆H₂(R ¹)₂NH(R ²)₂]⁺ClO ₄ ^– (R ¹=H,R ²=CH₃, C₂H₅ orvice versa) are formed as intermediates in the cross-coupling reaction; they undergo oxidation to imino-4-benzoquinone (9) and its corresponding derivatives by cerium(IV) ions in high yields. The mechanism of this process is discussed.

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Durch Cer(IV)-Ionen induzierte oxidative Kreuzkupplung einiger 2,6- und N,N-disubstituierter Anilinderivate mit 4-Aminophenol in wässriger Perchlorsäure

Zusammenfassung Die Oxidation von Mischungen von 2,6-Dimethylanilin (1), N,N-Dimethylanilin (2), 2,6-Diethylanilin (3), N,N-Diethylanilin (4), N-Methylanilin (5), 2,6-Difluoranolin (6) und 2,3,5,6-Tetrafluoranilin (7) mit 4-Aminophenol (8) durch Cer(IV)-Ionen in wässriger Perchlorsäure wurde untersucht. Als Zwischenprodukte der Kreuzkupplungsreaktion treten die Indoanilinsalze [O=C₆H₄=N-C₆H₂(R ¹)₂NH(R ²)₂]⁺ClO ₄ ^– (R ¹=H,R ²=CH₃, C₂H₅ oder umgekehrt) auf. Diese werden durch Cer(IV)-Ionen in hohen Ausbeuten zu Imino-4-benzochinon (9) und seinen entsprechenden Derivaten oxidiert. Der Mechanismus dieses Vorgangs wird diskutiert.

     

Ringsubstituierte [1]titanocenophane

The ring-substituted bis(cyclopentadienyl)silanesMe ₂Si(C₅H₅) (MeC₅H₄) (1a) andMe ₂Si(MeC₅H₄)₂ (2a) could be prepared by the reactions ofMe ₂SiCl₂ with C₅H₅Na andMeC₅H₄Na or only withMeC₅H₄Na, respectively. Metallation of1 a or2 a withn-BuLi and following reaction with TiCl₄ led to the first ringsubstituted [1]titanocenophanes,Me ₂Si(C₅H₄) (MeC₅H₃)TiCl₂ (1 b) orMe ₂Si(MeC₅H₃)₂ TiCl₂ (2 b), respectively. On reaction with NaI,1 b yieldedMe ₂Si(C₅H₄) (MeC₅H₃)TiI₂ (1 c). Structural assignments of the compounds could be made on the basis of their¹H NMR spectra.

     

An Ab Initio Study and NBO Analysis of the Stability and Conformational Properties of Hexakis(trimethylelementhyl)benzene (Element = C,Si, Ge,and Sn)

Ab initio molecular orbital and density functional theory were used to investigate energetic and structural properties of the various conformations of hexa-tertbutylbenzene (1), hexakis(trimethylsilyl)benzene (2), hexakis (trimethylgermyl)benzene (3), and hexakis(trimethylstannyl)benzene (4). HF/3-21G//HF/3-21G and B3LYP/3-21G//HF/3-21G results revealed that the Twist-Boat (TB) conformer of compound 1 is more stable than the 1-Chair (C), 1-Boat (B), and 1-Planar (P) conformers. B3LYP/3-21G//HF/3-21G results show that the 1- TB conformer is more stable than 1- C, 1- B, and 1- P conformers of about 1.13, 4.34, and 99.94 kcal mol^?1 , respectively. Contrary to the stability order of compound 1 conformers, the C conformer of compounds 2–4 is more stable than TB, B, and P conformations, as calculated by B3LYP/3-21G//HF/3-21G and HF/3-21G//HF/3-21G levels of theory. The energy gap between the C and P conformers in compounds 1–4 is decreased in the following order: ΔE(4: C, P) < ΔE (3: C, P) < ΔE(2: C, P) < ΔE (1: C, P). This fact can be explained in terms of the increase of C _aromatic -M (M═C, Si, Ge, and Sn) bond lengths and the decrease of steric (van der Waals) repulsions in the previously discussed compounds. For compounds 1–3, the calculations were also performed at the B3LYP/ 6-31G*//HF/3-21G level of theory. However, the comparison showed that the results at B3LYP/3-21G//HF/3-21G methods correlated well with those obtained at the B3LYP/6-31G*// HF/6-31G method. Further, NBO analysis revealed that in compounds 1–4, the resonance energy associated with the σ_M-C1 to σ*_C2-C3 delocalization is 5.20, 9.68, 11.15, and 12.27 kcal mol^?1, respectively. These resonance energy values could explain the easiness of the ring flipping processes of C, B, and TB conformers of compounds 4 to 1. Also, the NBO results showed that by an increase of the σ_M-C1 → σ *_C2-C3 resonance energies in compounds 1–4, the σ_M-C1 bonding orbital occupancies decrease. This fact could fairly explain the increase of the C_aryl-M bond length from compound 1 to 4. The NBO results are also in good agreement with the calculated energy barriers for the ring flipping of the chair conformations in compounds 1–4, as calculated by B3LYP and HF methods.     

AB initio study of the structure, isomerism, and vibrational spectra of LiClO3, NaClO3, and KClO3

The geometrical structure, force fields, and vibrational spectra of the ClO ₃ ^? ion and LiClO₃, NaClO₃, and KClO₃ molecules are studied using the Hartree-Fock (HF) method and second-order Möller-Plesset (MP2) perturbation theory in double-zeta basis sets complemented with polarization and diffuse functions. Routes of intramolecular rearrangements corresponding to migration of the M⁺ cations around the ClO ₃ ^? anion are investigated. The calculations showed that the molecular structure of alkaline metal chlorates changes in the series LiClO₃ → NaClO₃ → KClO₃. The LiClO₃ molecule has an essentially bidentate configuration of C_s symmetry; the KClO₃ molecule has tridentate coordination of C_3v symmetry. The NaClO₃ molecule exists as two isomeric forms having similar energies: tridentate (C_3v) and bidentate (C_s) forms separated by a low potential barrier (199 cm^?1 ? HF, 170 cm^?1 ? MP2); the energy differences between the isomers are ΔE(C_s ? C_3v)=?0.5 (HF), 0.4 kJ/mole (MP2). The theoretical vibrational spectra of molecules agree with the available experimental data.     

Investigations on electric properties of polymers—V: On the a.c. conductivity of polyphenylacetylenes

The electric conductivity of polyphenylacetylene with various physical and isomeric structures (cis-cisoidal, cis-transoidal and trans-cisoidal) was investigated over the frequency and temperature ranges of 10-10⁵ Hz and 273–347 K, respectively. The transient currents from polyphenylacetylene having cis-cisoidal structure were also studied at 293 K. It was found that a.c. conductivity of cis-cisoidal polymer can be explained in terms of a hopping mechanism. The type of mechanism (classical or quantum) depends both on frequency and temperature. At temperatures <284 K and high frequencies, the quantum mechanism (predominantly by single hops) is involved. As frequency decreases and temperature increases, there is a gradual passing to the classical mechanism (many multiple hops) and then to the Maxwell-Wagner conduction. The electric properties of cis-transoidal polymer are similar to those of trans-cisoidal one, but are different from those for the cis-cisoidal structure. The quantum hopping mechanism, almost entirely involving single hops, seems to predominate in these two polymers. Adsorption of oxygen decreases both conductivity and dielectric constant, as compared with those in nitrogen, only in the case of cis-cisoidal polymer.     

[Boranato-bis(dimethylphosphonium-methylid)]-Komplexe der do- und d10-Metalle: Li,Be, Mg,Zn, Cd,Hg, Al und Ga

Dehydrohalogenation and metallation of boranato-bis-trimethylphosphonium salts (1), using two equivalents of a lithiumalkyl in tetrahydrofuran, leads to a solvated organolithium reagent H₂B[(CH₃)₂PCH₂]₂Li (3) which can be converted into a 1:1n1-complex with tetramethylethylenediamin (4).3 reacts with anhydrous metal(II) halides to form spirocyclic coordination compounds of the type H₂B[(CH₃)₂PCH₂]₂ M[CH₂P(CH₃)₂]₂BH₂ (5–9,M=Be, Mg, Zn, Cd, Hg). The reaction of [(CH₃)₃PBH₂P(CH₃)₃]Br (1) with lithium tetramethylmetalates Li[M(CH₃)₄],M=Al, Ga, on heating in the absence of a solvent affords the metallocycles H₂B[(CH₃)₂PCH₂]₂ M(CH₃)₂ (10, 11) with evolution of methane. The products can be sublimed from the reaction mixture. The proposed structures of the new compounds, with tetrahedrally coordinated central atoms and strong covalent metal-carbon interactions, are supported by mass, IR and¹H,⁷Li,¹¹B,¹³C, and³¹P NMR spectra. Compound9 represents a rare case of a tetracoordinate organomercurial, compound5 is the first nonionic tetraalkylberyllate.